Bi-stem gripping apparatus

ABSTRACT

An apparatus (23) is constructed having a pair of side gripping members (32, 34) which are pivotally coupled by hinges to an intermediate gripping member (36). These gripping members (32, 34, 36) have a l/d (length-to-diameter) ratio of approximately 5:1 to distribute compressive forces over a relatively large area. Inner gripping regions (46, 48, 50) of the members (32, 34, 36) are configured having frictional surfaces (46, 48, 50) which frictionally grip a tubular structure, such as a bi-stem (12). A latch (51) having catches (56) is positioned on one of side gripping members (34), and a catch (62) is positioned on the opposite side member (32) for engaging the catches (56), latching the apparatus (23) closed around the bi-stem (12). Handles (68, 70) are centrally affixed to an exterior region of side members (32, 34) and allow the apparatus (23) to be readily closed around the bi-stem (12) and also allow manipulation of the bi-stem (12). These handles may be removed when the apparatus (23) is used as a repair device.

ORIGIN OF THE INVENTION

The invention described herein was made by an employee of the UnitedStates Government and may be manufactured and used by or for theGovernment for Government purposes without the payment of any royaltiesthereon or therefor.

TECHNICAL FIELD

This invention relates generally to devices for gripping cylindricalobjects and more particularly to a device having frictional grippingsurfaces which distribute the gripping force over a relatively largearea of the cylindrical object.

BACKGROUND OF THE INVENTION

As the technologies relating to space travel have improved, it hasbecome desirable to deploy satellites in either orbital positions aroundstellar bodies, including Earth, or to direct satellites in trajectoriescalculated to fly by or to land on stellar bodies in order to collectdata about them.

Increasingly, these satellites are being initially deployed, orsometimes repaired, by extravehicular activities (EVA) crew men who,appropriately garbed, exit a manned spacecraft to accomplish thesetasks. The deployment of satellites involves several steps in which asatellite is transformed from a compact, tightly packaged unitconfigured to be shipped into orbit to an unwieldy apparatus which, insome cases, have large solar panels resembling wings, sails, or otherconfigurations. Additionally, antennas and various types of equipmentmust be electromechanically deployed and supported by struts which insome manner must be compact for shipment into space but capable of beingextended during deployment of the satellite.

One such device which is capable of being compactly stored for deliveryinto space yet extendable to form a support strut once in space istermed a bi-stem. It consists of exterior and interior thin, stainlesssteel bands, with the exterior band configured to laterally encircle theinterior band to form a tubular structure. In order to store these bandsfor delivery into space, the bands are laterally straightened, and eachis rolled onto a roller which is mounted in a cassette. Once in space,the rollers are driven so as to drive the bands out of the cassette,allowing the exterior band to encircle the inner band and form abi-stem.

Problems have occasionally arisen when attempting to drive the bands outof the cassette, which causes them to become jammed in the cassette.When this occurs, and if the deployment of the satellite is during amanned flight, the astronauts may attempt to free the jammed bi-stem. Todo this, they would have to grasp the bi-stem with a gloved hand andattempt to pull it out of the cassette. The problem with this is that ahuman hand inside a spacesuit glove cannot distribute the forcenecessary to grasp the bi-stem without crushing or otherwise damagingit. Also, the spacesuit glove is relatively slippery against the smoothbi-stem and would tend to slip. Further, since the bi-stem has anexposed sharp longitudinal seam, the possibility exists that a glovecould be punctured by this seam. Thus, in the event that the bi-stemcannot be easily freed, the equipment it supports cannot be properlydeployed. In the instance where the jammed bi-stem is used to support ordeploy one of several solar panels which generates electrical power forthe satellite, then the remaining solar panels may not be able toprovide sufficient electrical power for the satellite, which may thenbecome partially or totally disabled. This would be an obviouslyexpensive failure.

It is an object of the present invention to provide a device forapplication of gripping forces to a cylindrical object, the grippingforces being distributed over a relatively large surface of thecylindrical object.

It is a further object of this invention to provide a device which maybe used by extravehicular crew men to free a jammed bi-stem from acassette in which it is stored.

SUMMARY OF THE INVENTION

In accordance with this invention, a gripping apparatus for grippingtubular structures is constructed having a pair of elongated sidegripping members each having arcuate inner gripping regions, and eachpivotally coupled to an elongated central gripping member having a likeconfigured arcuate inner gripping region. These inner gripping regionshave frictional surfaces to prevent slippage of the apparatus on thetubular structure, and the pair of elongated side gripping members areequipped with a latch to lock the apparatus around the tubularstructure. A handle is provided on each side gripping member and extendsin normal relation therefrom to allow the cylindrical structure to bemanipulated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view illustrating a jammed bi-stem and anastronaut attempting to free the bi-stem with the bi-stem grippingapparatus of the present invention.

FIG. 2 is a pictorial view of a bi-stem gripping apparatus clamped ontoa bi-stem.

FIG. 3 is an end elevational view of a bi-stem gripping apparatuspositioned to be clamped around a bi-stem.

FIG. 4 is an end elevational view of a bi-stem gripping apparatusclamped around a bi-stem.

FIGS. 5a and 5b are sectional views of a bi-stem, with FIG. 5a showingthe relaxed configuration of the bi-stem, and FIG. 5b showing thecompressed configuration of the bi-stem.

FIG. 6 is a diagrammatic view of a pair of rollers onto which bands thatform a bi-stem are stored, and which further illustrates the positioningof these rollers with respect to the formation of a bi-stem.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a solar array 10 is shown being deployedby bi-stems 12 and 14 positioned on sides 16 and 18, respectively, ofarray 10. Bi-stems 12 and 14 are stored in and deployed from cassettes20 and 22, respectively, and, as shown, an astronaut is working to freeupper bi-stem 12, it being assumed that it has incurred a jammedcondition within its cassette 20. In order to attempt to dislodgebi-stem 12 from its jammed condition, the astronaut has clamped abi-stem gripping apparatus 23 onto partially extended bi-stem 12 whichallows him to safely manipulate bi-stem 12 while applying the necessaryforce to free the jam.

Bi-stem gripping apparatus 23 is more particularly illustrated in FIGS.2, 3, and 4, and is shown in FIGS. 2 and 4 gripping bi-stem 12. Bi-stem12 is constructed of a pair of thin, stainless steel bands 24 and 26(FIGS. 5a, 5b, and 6) which are approximately 0.005" thick andapproximately 2.35" wide. These bands are rolled onto rollers 25 and 27(FIG. 6) within a cassette (FIG. 1), with rollers 25 and 27 beingpositioned to allow bands 24 and 26 to concentrically encircle oneanother when rollers 25 and 27 are driven in a direction which drivesbands 24 and 26 out of the cassette. Edges 28 and 30 of bands 24 and 26,respectively, are positioned 180° apart and are gapped to providebi-stem 12 with a diameter of approximately 7/8" when relaxed andapproximately 3/4" when compressed until edges 30 of inner band 26 abut.

Gripping apparatus 23, when closed about bi-stem 12 (FIGS. 3 and 4),forms a generally tubular structure which is laterally trisected intothree equally sized gripping members 32, 34, and 36. Intermediategripping member 36 is provided with hinge members 35 and 37, which arepivotally connected to hinge members 39 and 41 of side gripping members32 and 34. These gripping members, when closed, have an inside diameterof approximately 3/4" and a length of approximately 5". Thus, apparatus23 has a length/diameter ratio of approximately 5:1. Apparatus 23 isconstructed as such to distribute the compressive forces applied tobi-stem 12 over at least a predetermined length of bi-stem 12 (typically5") to prevent it from being crushed. Additionally, these compressiveforces applied by members 32, 34, and 36 are radially distributed aroundan axis 38 extending longitudinally through bi-stem 12, as indicated byvectors 40, 42, and 44, which are radially spaced approximately 120°apart. It is necessary to vector these forces as such in order touniformly compress bi-stem 12. A construction of apparatus 23 havingonly two opposed gripping members is eliminated because of the fragileconstruction of bi-stem 22 (bands which are 0.005" thick). These twoopposed gripping members would tend to compress bi-stem 22 into anoblong configuration, possibly damaging it.

Gripping members 32, 34, and 36 have arcuate inner gripping surfaces 46,48, and 50, respectively, which are constructed of a frictionalmaterial. This material generally consists of a gum stock siliconerubber, such as G.E. 5211, which is manufactured by General ElectricCompany. It has been discovered that this particular compound issuitable for use in the vacuum and temperature conditions of space. Thisrubber is molded under heat and pressure into a sheet approximately 1/8"thick, having a durometer of approximately 25. These sheets are cut tosize and bonded, as by rivets (not shown), to inner regions of members32, 34, and 36, respectively.

A ratchet-type latch 51 positioned on side member 34 allows bi-stemgripping apparatus 23 to be locked in place around bi-stem 12. Latch 51is constructed having a pawl member 52 (FIGS. 3 and 4) pivotally mountedto exterior region 54 of member 34. Pawl 52 has a linear series ofcatches 56 positioned on end 58, and a spring 60 biases end 58 inwardtoward axis 38 when apparatus 23 is closed around bi-stem 12. A catch 62on opposite side member 32 engages catches 56 of pawl 52 and enablesapparatus 23 to be latched at increasingly reduced diameters aroundbi-stem 12 until edges 64 and 66 of side members 32 and 34 abut. At thislatched position, edges 30 of band 26 is also in an abutting relation,and bi-stem 12 is compressed to its minimum diameter of approximately3/4". Alternately, a cam-type latch or other latches suitable for use inspace (not shown) may be used to pull members 32, 34, and 36 togetherand secure them in a latched configuration.

If desired, handles 68 and 70 may be made removable and mounted on stubshafts 72 (only one shown in FIG. 3) of side gripping members 32 and 34.These stub shafts 72 may incorporate openings 74 (only one shown), whichare engaged by ball-type detent catches (not shown) built into handles68 and 70. In the case where apparatus 23 is to be used in space, thesedetent catches would be PIP pin-type latches, which incorporate locks onthe detent balls, providing positive latched engagement between handles68 and 70 and stub shafts 72. In order to unlatch handles 68 and 70,buttons 69 and 71 are depressed, which disengage the balls, engagingopenings 74 and enabling handles 68 and 70 to be removed. A tetheringring 78 is centrally affixed to an outer surface 80 of intermediatemember 36 and provides a convenient point to which a lanyard (not shown)may be affixed. This lanyard would be attached at a opposite end to asecond tethering point affixed to a structure (not shown). Tetheringring 78 may be omitted when apparatus 23 is to be used in a gravityenvironment, but is useful in space to prevent apparatus 23 frominadvertently drifting away and becoming lost.

In operation, and assuming that bi-stem gripping apparatus 23 is to beused in a microgravity environment, FIG. 1 illustrates an astronautattempting to free jammed bi-stem 12. As shown, apparatus 23 is attachedaround bi-stem 12 by using handles 68 and 70 to radially compressbi-stem 12 to its minimum diameter, e.g., until edges 30 of band 26 abut(FIGS. 4 and 5b). In this configuration, frictional surfaces 46, 48, and50 are fully engaged with bi-stem 12, and the astronaut is able to pullbi-stem 12 from its cassette 20 by applying force to handles 68 and 70in a direction outward from cassette 20.

In the instance where bi-stem 12 has become damaged, as frommicrometeorite hits or inadvertent collisions with other structures,apparatus 23 may be used as a splint or repair device. In this instance,a bent bi-stem may be straightened by clamping apparatus 23 around thebent region (not shown) of a bi-stem. As apparatus 23 is levered closedby handles 68 and 70, the bi-stem will be straightened. After latch 51is engaged, handles 68 and 70 may then be removed and apparatus 22 leftin place as a support for the damaged region. In the instance where itis anticipated that apparatus 23 is to be used as a repair device, itmay be constructed longer than 5" to further distribute stresses over alarger area of the bi-stem.

From the foregoing, it is apparent that the applicant has provided anapparatus for securely gripping cylindrical objects while applying anevenly distributed gripping force along the length thereof;specifically, applicant has provided a bi-stem gripping apparatus 23which may be used to manipulate a jammed bi-stem until it is free.Additionally, as desired, this apparatus may be used as a repair deviceto support a damaged bi-stem.

What is claimed is:
 1. A gripping apparatus for gripping andmanipulating cylindrical structures, said apparatus comprising:a pair ofelongated side gripping members and an elongated intermediate connectinggripping member secured in pivotal relation therebetween, said membershaving arcuate inner gripping regions; frictional gripping means securedto said inner gripping regions for frictionally gripping saidstructures; latching means for latching said pair of elongated sidegripping members and said elongated intermediate gripping member aroundsaid cylindrical structures, said members disposed for application ofevenly distributed gripping forces to said cylindrical structuresresponsive to latching by said latching means; and a pair of handlemeans, each positioned on an exterior region of each of said pair ofside gripping members, for manipulating said cylindrical structures. 2.A gripping apparatus as set forth in claim 1 wherein said frictionalgripping means comprises a gum stock silicone rubber adapted for use ina vacuum.
 3. A gripping apparatus as set forth in claim 2 wherein saidhandle means are centrally disposed on said exterior region of said pairof side gripping members, and said handle means extending outward normalto said side gripping members.
 4. A gripping apparatus as set forth inclaim 3 wherein said latching means comprises a pawl member pivotallydisposed on an outer region of one of said pair of side grippingmembers, said pawl having a spring which biases an end of said pawlinward, said end having a linear series of catches disposed thereon anda mating catch disposed on an outer region of an opposite said sidegripping member, said linear series of catches being aligned with saidcatch, whereby said gripping members are latched at increasingly reduceddiameter positions around said structure until latched edges of saidpair of side gripping members abut.
 5. A gripping apparatus as set forthin claim 1 wherein said elongated gripping members are of apredetermined length/diameter ratio comprising approximately 5":1"ratio, whereby the concentration of radially compressive forces on saidstructure is prevented.
 6. A gripping apparatus configured for use in amicrogravity environment for gripping and radially compressing a bi-stemconstructed of first and second thin, flexible steel bands disposed inconcentric relation, said bi-stem having an axis extendinglongitudinally therethrough, and said gripping apparatus comprising apair of side gripping members and an intermediate connecting grippingmember pivotally disposed therebetween, said intermediate connectingmember having a tethering ring affixed to an exterior region thereof,said gripping members having arcuate inner gripping regions configuredto frictionally grip and radially compress said bi-stem about said axis,and latching means disposed on outer regions of said side grippingmembers for latching said gripping members around said bi-stem as saidbi-stem is gripped and compressed, and removable handle means centrallydisposed on exterior regions of each of said side gripping members, saidhandle means extending outward therefrom, for closing said grippingmembers about said bi-stem and manipulating said bi-stem, whereby threediscrete vectors of force are applied by said gripping members to saidbi-stem, said vectors being radially spaced approximately 120° aboutsaid axis.